Process of making potash alum



PATENT OFFICE.

THQKAS H. ,WRIGI-IT, OF LDS AIIGBLES, CALIFORNIA.

Specification of letterslatent.

rItOCESS OF MAKING POTASH ALUM.

Patented Nov. 8, 1921.

No Drawing. 'originalgapplication filed Kay 28, 1919, ScrlaINo; 300,404.Divided and this application filed May 11, 1920. Serial No. 380,559.

T001? whom it may concern:

Bcit knownthat I, THoMAs H. WRIGHT, a citizenof the United States,residing at Los Angeles, in the countyof Los Angeles and State ofCalifornia, have invented new and useful Improvements in Processes ofducing potash alum, KAHSOJ 12H O and other products of commercial valuefrom soluble potassium compounds, derived either from soluble potassiumminerals or soluble potassium compounds derived from any other source,by means of crude aluminum sulfate.

It is an object of this invention to provide a simpleand inexpensiveprocess of making potash alum by the use of aqueous solutions ofre-agents which need not be of chemical purity.

The presentapplication is a division of my U. S. patent for a process ofmaking potash alum, No. 1,359,011, dated November 16, 1920, in whichclaims were limited to magnesium sulfate, while the present inventioncovers sodium sulfate.

My invention consists in the steps of the process hereinafter describedand claimed.

I take water soluble potassium compounds which may be derived fromdeposits in the semiarid regions of the western part of the UnitedStates, or soluble potassium compounds derived from any other source.For example, a potassium compound mineral found in deposits in SanBernardino county, California, is composed of the followin ingredients:magnesium sulfate 60 to 6%, sodium sulfate 6 to 10%, potassium sulfate 8to 18%, and lesser amounts of sodium chlorid, silica, calcium sulfate,etc.

The aluminum sulfate I use in my process is a crude material. I usealuminum sulfate derived from large deposits in the counties of Kern andSan Bernardino, State of California, the chemical analysis of whichshows ap roximately 75% of aluminum sulfate, Al S0,) and an insolubleresidue of 25%.

The crude potassium compound obtained from San Bernardino county istreated with water, preferably heated, to dissolve the solubleconstituents, which, as stated, consist of magnesium, sodium andpotassium sulfates. The solution is decanted from the insoluble residueand subjected to fractional crystallization in order to removepractisally all thema nesium and sodium sulfates, leavingthe mot erliquor containing all the potassium sulfate mixed with about 5% ofmagnesium sulfate and from 1% to 2% of sodiutn sulfate. This motherliquor is now treated with a solution of aluminum sulfate, the amount ofaluminum sulfate to potassium sulfate being taken in molecularpro-POItiOD.

The reaction is carried on at a temperature not exceeding 92 C. and thepreferred den sity of the solutions is 25 to 30 B. for the mother liquorand 40 B. for the aluminum sulfate.

with the following equation:

The solution, on cooling, produces crystals of practically pure potashalum, which are removed from the mother liquor in any suitable way. Theremaining mother liquor may be thrown away or used again to treatanqther quantity of crude potassium materia My method of treatmentvaries according to the nature of the acid radical of the potassiumsalt. For example, I may have p0- tassium chlorid mixed with sodiumchlorid in the potassium liquor to be treated and I have discovered thatthe addition of magnesium sulfate or of sodium sulfate, or a mixture ofthe two in connection with the aluminum sulfate produces a perfectreaction, enabling the potash alum to crystallize out in a pure state,as expressed by the following equation:

It should be noted that the sulfuric acid radical supplied to the potashalum is also derived from the magnesium sulfate or the sodium sulfate,or a mixture of the two.

It is necessary that the mixture be neutral or sli htly acid, and it istherefore advisable to add a small quantity of sulfuric acid until themixture re-acts slightly acid. In a case where the potassium saltsolution contains potassium carbonate sulfuric acid is added until thegeneration of carbonic dioxid ceases in accordance with the followingequation:

,mixed together. WVater is thenadded to produce the proper. degree ofdensity'and the mixture is heated to a temperature not to exceed 92 C.It is then cooled and the potashjalum crystals are formed. The latterare then filtered from the liquid in any desired manner.

claimed.

Various changes may be made without departing from the spirit of myinvention as I claim:

1. A process of making potash alum, comprising treating an alkaline,aqueous, mineral potassium chlorid solution with sodium sulfate,rendering slightly acid, adding aluminum sulfate, and removing thepotash alum thus formed from the mixture.

2. A process of making potash alum, comprising mixing mineral potassiumchlorid with sodium sulfate, rendering slightly acid, adding aluminumsulfate in an aqueous solution not to exceed a density of approximately40 B., heating the mixture to a temperature not to exceed 92 (1, therebyforming potash alum, cooling the mixture, thereby forming crystals ofpotash alum, and removing said crystals from the mixture.

In testimony whereof I have signed my name to this specification.

T. H. WRIGHT.

